NASCAR’s continued struggle to balance cost, safety and competitiveness led to using PJ1 Track Bite in 2017 at Bristol Motor Speedway. Since then it’s been used (mostly successfully) at other tracks. So what is it and how does it work?
Note: This post replaces an earlier post published in July 2017 and adds new information and insights.
PJ1? VHT? Track Bite? TrackBite?
The correct name is PJ1 Track Bite. The traction-enhancing liquid was originally developed by the Sperex corporation as a high-temperature coating for NASA.
Sperex spun the material off to its VHT label and the product was primarily purchased and used by drag racers. In 1989, P.J. Harvey purchased the product (and other Sperex assets of Sperex) and marketed it under his own brand: PJ1 Track Bite.
PJ1 TrackBite is so common in the drag racing world that every forum has at least one thread about how to make your own. The original costs about $50 per gallon.)
What is it?
In a word: proprietary. The MSDS (Materials Safety Data Sheet) is a government-mandated report that must detail any hazardous chemicals in a product, and explain how they should be handled and disposed of. Here’s the most recent MSDS I could find for PJ1 Track Bite.
The laundry list of chemicals at the top (isopropanal, n-hexane, ehanol, hexane, methylcyclopentane and toluene) are all solvents. They are carriers for the main (proprietary) ingredient.
For example, nail polish comes suspended in solvents, which allows it to be put on your nails in liquid form. The solvent evaporates and leaves behind the actual nail enamel. It’s the same here: the active chemicals are only 10-20% of the liquid and the rest are just carriers that evaporate after application.
They don’t have to disclose the active ingredient because it’s proprietary and not hazardous.
What Do We Know About It?
It’s a resin. A resin is a solid or viscous (i.e. thick) liquid that can be polymerized. Plants ooze resins to protect themselves when injured. If you’ve ever had to take down a pine tree, you know exactly what I’m talking about. Rosin (like for a violin bow) is also a resin.
Polymerized just means a bunch of organic molecules that had been hanging around by themselves hold hands. Shellac and lacquer are examples of resins: They go on liquid (gooey liquid) and then polymerize to make a hard coating. Amber is polymerized tree sap.
We can learn something, however, in the material’s origins as a high-temperature coating. Sperex’s original work was for the Space Shuttle. Their high-temperature paints for exhaust systems, firewalls, manifolds, etc. are still available from PJ1. The picture below is from a NASA Technical Report from 1978 and I included it just because it shows the legendary drag racer Carol “Bunny” Burkett, whom I was shocked to find does not have a Wikipedia page.
PJ1 Track Bite Isn’t Sticky
The challenge for high-temperature coatings that they not only have to survive high temperatures, they have to stick to whatever they are coating. The picture below shows that can be a problem even when you’re only talking about a really hot summer.
Have you ever noticed that peanut butter likes to stick to itself rather than the bread? The paint in the picture is doing exactly that. It’s spalling: it would rather stick to itself than the brick.
Rubber is the same way. Rubber will stick to asphalt, but it would much rather stick to rubber. The proof of that is the marbles you find at the edge of the track and the coating of rubber pieces found on tires, bodies, walls, etc. after a race.
PJ1 TrackBite doesn’t work because it’s sticky. In fact, it’s consistency when applied isn’t very different from water.
But even when it dries, it’s not really that sticky. It doesn’t work the same way that spraying soda in your pit box helps your pit crew not slip around. There’s a huge difference between the heat generated by the pit crew’s sneakers and the heat generated by the tires on a car going 190 mph.
The Physics of Grip and PJ1 Track Bite
- Friction (grip) is the atoms of one surface grabbing the atoms of another surface. The stronger the two surfaces hold onto each other, the more grip.
- Most materials like sticking to themselves more than they like sticking to other materials.
- Adhesive friction is part of the overall friction between tires and track. Think of adhesive friction as if you’re walking down the sidewalk in on a very warm day and you step on a piece of gum — but on an atomic scale.
- The rubber on the track grabs the rubber on the tires to create adhesive friction. Each rubber-rubber bond holds the car to the track.
- These bonds are constantly being made, but also being broken. Otherwise, cars would get stuck in the track like a saber-toothed tiger in the LaBrea Tar Pits.
- PJ1 works by helping the track pick up rubber.
Pros and Cons
PRO: Rain Resistance Rain will wash rubber from the track, but PJ1 Track Bite is water resistant. It won’t stand up to a deluge, but a little rain won’t rinse it off the track.
PRO: Ease of Application. The instructions for application to oval tracks show that the most important part of application is cleaning the track. After that, the material is simply sprayed on.
PRO: Better Racing. In more cases than not, the use of PJ1 Track Bite has improved the racing. There have been some problems, but those seem to have been from the application of the product, not the product itself.
PRO and CON: Limited Lifetime: Even without water or oil, PJ1 Track Bite has a limited lifespan. When enough rubber gets laid down on the track, the forces of adhesion of the rubber to itself wins and the rubber will come up as marbles, taking the PJ1 with it. (It’s like when you put a lot of labels on a file folder and they all come up at once.) But it also means you’re not making any permanent changes to the track, so you can try different things.
Possible CON: Oil Solubility. Most things that aren’t soluble in water are soluble in oil. Drivers would be wise to avoid a spot on the track where a car leaked oil. The grip of that particular section of track might be significantly different that the rest of the track.
CON: Solvents. In addition to the solvents already in there, you are instructed to dilute the concentrate with Isopropyl Alcohol or Methanol. Methanol, in particular, is a solvent you want to minimize your exposure to.
TrackBite helps tracks rubber up faster. Selective application allows NASCAR to enhance one or more lines and widen the racing groove. PJ1 Track Bite is relatively easy to apply and mostly water resistant, but it does wear off with time and use. On the negative side, there is an art to applying it and no guarantee that two applications will produce the same results. A lot of the solvents it uses aren’t great for humans or the environment.